Anchor handling vessel

ABSTRACT

This invention relates to improvements in auxiliary vessels of the type used to handle the anchors, buoys, etc., used in mooring large ships such as offshore drilling vessels. The improvement comprises a bridge structure elevated above, and movable longitudinally of, the deck of the anchor handling vessel. The bridge structure includes an anti-friction support for a winch line and, when positioned near the stern of the vessel, greatly reduces the forces necessary for breaking an anchor or similar object over the stern and onto the deck of the vessel. In the preferred form, the bridge structure also mounts a powered winch or bridge crane movable transversely of the bridge which may be used for moving anchors to other cargo about the deck. This abstract is not to be construed in any way to describe or limit the invention set forth below.

United States Patent 1 Pease 1 1 ANCHOR HANDLING VESSEL [75] Inventor: Floyd T. Pease, Houston, Tex.

[73] Assignee: The Offshore Company, Houston,

Tex.

[22] Filed: Oct. 25, 1973 [21] Appl. No.: 409,395

[52] US. Cl 114/206 R; 114/210; 114/235 R [51] Int. Cl B63b 21/22 [58] Field of Search... 114/206, 43.5, 235 R, 235 B,

1 1 June 17, 1975 Primary Examiner-Trygve M. Blix Assistant E.raminerSherman D. Basinger Attorney, Agent, or Firm-Joe E. Edwards; W. Ronald Robins; Jack R. Springgate {57] ABSTRACT This invention relates to improvements in auxiliary vessels of the type used to handle the anchors, buoys, etc., used in mooring large ships such as offshore drilling vessels. The improvement comprises a bridge structure elevated above, and movable longitudinally of, the deck of the anchor handling vessel. The bridge structure includes an anti-friction support for a winch line and, when positioned near the stern of the vessel, greatly reduces the forces necessary for breaking an anchor or similar object over the stern and onto the deck of the vessel. in the preferred form, the bridge structure also mounts a powered winch or bridge crane movable transversely of the bridge which may be used for moving anchors to other cargo about the deck. This abstract is not to be construed in any way to describe or limit the invention set forth below.

7 Claims, 4 Drawing Figures PATENTEDJUN 1 1 ms 3, 889,621 SHEEI 1 PRIOR ART J TDRIEZR ART ANCHOR HANDLING VESSEL This invention relates generally to auxiliary or anchor handling vessels of the type used to assist larger vessels in deploying and retrieving anchors, buoys, and related mooring apparatus. More specifically it relates to an improvement which greatly reduces the amount of force necessary for lifting or breaking" an anchor or other heavy object over the stern and onto the deck of the anchor handling vessel.

In brief, the invention involves the provision of an elevated bridge structure movable longitudinally of the deck of the anchor handling vessel on parallel rails or tracks. The winch line used in lifting the achor, or similar object, is passed over anti-friction support means on the bridge, such as idler rollers or sheaves, and thence over the stern of the vessel to the object being lifted. The bridge structure, which is positioned near the stern of the vessel when an anchor (or other object) is being lifted onto the deck, thus serves to provide a movable elevated support for the winch line at the stern. This increases the angle between the anchor and winch line as the anchor is being lifted, thereby decreasing the force necessary to lift the anchor onto the deck. Once the anchor is lifted to deck level, the movable bridge structure may also be used to transfer the anchor or other object to its desired position on the deck. In the preferred embodiment, a powered winch is also provided on the bridge structure and is movable transversely of the bridge to act as a bridge crane to assist in handling of the deck cargo.

The primary object of the invention is to provide an apparatus which reduces the winch force necessary for lifting an anchor or similar heavy object over the stern and onto the deck of an anchor handling vessel. Another object is to provide such a structure which may also be used in positioning cargo on the deck.

A further object is to provide such an apparatus wherein a movable bridge structure is provided above the deck and includes anti-friction support means for the main which line as well as a separate powered winch movable transversely of the bridge structure.

These and other objects and advantages of the invention will be apparent from the following drawings, specification and claims.

In the drawings, which form a part of the application, and in which like numerals indicate like parts;

FIG. 1 is a diagrammatic illustration of an auxiliary vessel being used to recover the anchor and related mooring apparatus of a larger vessel according to the conventional prior art practice;

FIG. 2 is an enlarged detail illustration showing the anchor and a portion of the anchor handling vessel of FIG. 1 in the position at which maximum winch pull occurs in lifting the anchor onto the deck of the vessel;

FIG. 3 is an isometric view of a vessel having the movable bridge structure of the present invention to assist in lifting the anchor over the stern of the vessel and placing it in its desired location on the deck; and

FIG. 4 is a view in side elevation of the stern portion of the vessel of FIG. 3 illustrating the stern most position of the movable bridge structure.

Referring now to FIG. 1, there is shown in auxiliary or anchor handling vessel such as is commonly used to assist another, usually larger vessel 12 in setting and retrieving its anchors and related mooring apparatus. Such auxiliary or anchor handling vessels are frequently used to assist offshore drilling vessels, semisubmersible rigs and the like in displaying and retrieving their anchor array. The vessel 12 is shown moored by an anchor 14 and a mooring line 16 of chain, wire rope or the like. The anchor in its set position also has connected to it a buoy pendant line 18 subtended from a surface buoy 20 (both shown in dotted lines in FIG. I). The buoy serves to mark the position of the anchor and the buoy line also serves as a winch line for retrieving the anchor.

The auxiliary anchor handling vessel 10, which has an elongated rear deck 22 with a powered winch 24 mounted thereon, may be used to dislodge and retrieve the anchor 14 when desired. In doing so, the surface buoy 20 is captured by the anchor handling vessel 10 and the buoy line 18 is connected to the line from winch 24 (all of which line may then be considered to be a winch line 26). The winch is operated to exert a pull through line 26 on the anchor 14 in a direction approximately parallel to the anchor flukes 14a so as to dislodge the anchor from the ocean floor. The anchor may then be winched up to the vessel 10 and stowed on the deck 22 for transport. Once the anchor 14 is aboard the handling vessel 10, the ships mooring line 16 may be released from the anchor and reeled aboard the vessel 12 for storage.

A principal problem with this procedure occurs as the anchor is pulled or broken" over the stern of the vessel onto the deck 22. This is illustrated in FIG. 2. As there shown, the vessel 10 commonly includes a stern roller 28 (although in some cases a curved chafir 4 plate may be substituted) to assist in breaking the anchor over the stern. However, as the upper end of the anchor nears the top of roller 28, the line 26 to winch 24 is in a nearly horizontal position. With the parts in this position, an excessive tension force must be exerted on the line 26 by the winch in order to generate sufficient vertical component of force to lift the anchor 14, trailing the heavy mooring line 16, over the roller 28 and onto the deck. Since most commonly used anchors, particularly those used for large vessels such as drilling rigs, semi-submersibles, etc., are relatively long, heavy and flat, the winch line must create an impractically large force moment as the anchor is lifted out of the water and onto the deck. Failure of the winch line 26 under high tension, would of course entail extreme danger to personnel and equipment on the vessel as well as the inconvenience, expense and delay of having to use an alternative procedure for retrieving the anchor.

One solution to the problem which has been proposed, and to some extent adopted, is to provide a pivoted elevated hoist on the stern of the vessel with an idler roller or sheave in the hoist for the winch line. With such an apparatus, the pivoted hoist is disposed over the stern as the anchor is being lifted and then is swung or pivoted onto the deck for further handling or stowage of the anchor. However, the necessary swinging or pivoting of the hoist can create a substantial personnel danger from the swinging anchor, particularly in rough seas, thereby reducing the desirability of the apparatus.

The present invention provides a means for overcom ing these prior art problems and of easily deploying and recovering mooring systems in rough as well as calm weather, as well as for safely transferring deck cargo and mooring system components between any two points on the deck.

Referring to FIG. 3, there is shown the anchor handling vessel with deck 22 for receiving the anchors and winch 24 with winch line 26 for raising the anchor 14, and including additionally apparatus according to present invention for assisting in the raising and handling of the anchor. A bridge structure, indicated generally at 30, is disposed transversely of the deck and means are provided for supporting the bridge structure elevated above the deck and movable longitudinally of the deck. In the preferred embodiment these support means comprise a pair of elevated tracks 32 mounted on suitable upright supports 34. The bridge structure 30 extends between the tracks and is mounted thereon by suitable anti-friction means such as rollers (now shown) so as to permit the bridge structure to move longitudinally along the tracks. The rear portions of tracks 32 are cantilevered beyond the stern of the vessel, as indicated at 320, so that the bridge 30 in its ex treme rearward position may extend outboard of the vessel. Suitable stops (now shown) are of course provided to prevent the bridge 30 from running off the end of tracks 32.

Power means are preferably provided for driving the bridge structure along the tracks. In the illustrated embodiment, the power means comprise a pair of drive pinions 36 on the bridge structure driven by drive shaft 38 from an electric motor 40 and driving against racks 42 provided on the tracks 32.

Anti-friction support means are provided on the bridge structure 30 for supporting the line 26 extending between the winch 24 and the anchor. In the preferred embodiment, these comprise a pair of idler rollers or sheaves 44 mounted about midway transversely on the upper side of the bridge structure so as to support the line 26 above the bridge structure.

The bridge structure 30 also mounts a bridge crane 45 comprising a trolley 46 movable transversely of the bridge structure and a powered winch 48 mounted on the trolley. The bridge crane 45 with its winch line 50 and book 52 (FIG. 4) may be used as a vertical hoist for carrying or dragging equipment between locations on the deck. Since the bridge crane is movable trans versely of the bridge structure and the bridge structure as a whole is movable longitudinally of the deck, the bridge crane may be positioned at any desired point above the deck 22 to assist in lifting and transferring cargo. As shown in FIGv 4, the bridge crane is of such a size that it can pass under the winch line 26 in sheaves 44 so as to be freely movable transversely of the bridge 30 at all times.

In operation, the bridge structure 30 may be moved onto the cantilevered ends 320 of tracks 32 so as to po sition the bridge structure and bridge crane outboard of the stern of the vessel. In this position the bridge crane 45 may be used in lifting lighter objects such as buoys from the water. Also, with the bridge structure in this outboard position, the winch line 26 will exert a direct upward pull on anchor 14 to provide maximum pull when dislodging the anchor from the seam bottom. Once the anchor is raised, the bridge structure 30 may be moved slightly inboard to approximately the position illustrated in FIG. 3 so as to provide both an upward and inboard pull on the anchor so as to lift it over anchor were being pulled directly over stern roller 28 by the winch.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention. Although the invention has been described in terms of handling anchors, it will be understood that the object being handled is not intended as a limitation and the invention and claims are equally applicable to the handling of other heavy objects as well.

What is claimed is:

1. An anchor handling apparatus comprising:

a buoyant vessel having a deck for receiving an anchor,

a pair of tracks disposed adjacent opposed sides of said deck and extending longitudinally of said deck,

an elevated transverse bridge structure extending between said tracks and movable longitudinally of said deck along said tracks.

a powered winch on said vessel for reeling in a line connectible to said anchor and extending generally longitudinally of said deck, and

anti-friction support means on said bridge structure intermediate said tracks for supporting said line extending generally longitudinally of said deck from said winch over said support means to said anchor,

said tracks being spaced from each other by a distance greater than the width of the anchor to be handled, so that said anchor may freely pass between said tracks, and the space between said tracks and above said deck being free of obstructions which would interfere with the movement of said anchor, whereby said anchor may be freely moved longitudinally of said deck between said tracks by said bridge structure and deposited at a desired location on said deck intermediate said tracks.

said tracks being essentially straight throughout their effective length and including a portion which is cantilevered beyond the edge of said deck during the operation of said bridge structure whereby said bridge structure may be selectively positioned outboard of said vessel.

2. The apparatus ofclaim 1 wherein power means are provided on said bridge structure for moving said bridge structure longitudinally of said deck, said power means comprising an electric motor powered driver on said bridge structure in driving engagement with one of said tracks whereby said bridge structure may be driven along said tracks in either direction longitudinally of said deck.

3. The apparatus of claim 1 wherein said anti-friction support means of said bridge structure comprise a pair of idler sheaves adapted to receive said line and support said line above said bridge structure, whereby frictional engagement between said line and said bridge structure is prevented.

4. An anchor handling apparatus comprising:

a buoyant vessel having a deck for receiving an anchor,

a pair of elevated tracks disposed adjacent opposed sides of said deck and extending longitudinally of said deck,

a transverse bridge structure extending between said tracks and movable longitudinally of said deck along said tracks,

a powered winch on said vessel for reeling in a line connectible to said anchor and extending generally longitudinally of said deck,

anti-friction support means on said bridge structure intermediate said tracks for supporting said line extending generally longitudinally of said deck from said winch over said support means to said anchor, and

a bridge crane mounted on said bridge structure and adapted to move transversely of said bridge structure.

5. In an anchor handling vessel having a winch adapted to reel in a line extending longitudinally of said vessel and connected to an anchor and a deck adapted to receive the anchor, the improvement comprising:

a pair of straight elevated tracks spaced from each other and disposed longitudinally of said deck,

a bridge structure disposed transversely of said deck,

and mounted on said tracks for movement longitudinally of said deck,

anti-friction support means on said bridge structure for supporting said line extending longitudinally of said deck between said anchor and said winch, and a bridge crane assembly mounted on said bridge structure and movable transversely of said deck along said bridge structure.

6. The apparatus of claim 5 wherein said anti-friction support means comprises at least one idler sheave disposed on top of said bridge structure to support said line above said bridge structure and wherein said idler sheave and said bridge crane are so configured that said bridge crane may pass freely under a line in said sheave.

7. An apparatus comprising:

a vessel having an elongated rear deck for receiving objects lifted over the stern of said vessel,

a winch on said deck with a winch line extending generally longitudinally of said deck and adapted to be connected to objects to be lifted onto the deck,

a pair of elevated tracks disposed longitudinally of said deck along opposite transverse edges thereof,

a bridge structure extending transversely between and mounted on said tracks for movement longitudinally of said deck,

an idler sheave on the upper side of said bridge structure adapted to receive and support said winch line above said bridge structure, and

a bridge crane mounted on said bridge structure for movement transversely thereof and adapted to pass freely under said winch line in said sheave. 

1. An anchor handling apparatus comprising: a buoyant vessel having a deck for receiving an anchor, a pair of tracks disposed adjacent opposed sides of said deck and extending longitudinally of said deck, an elevated transverse bridge structure extending between said tracks and movable longitudinally of said deck along said tracks, a powered winch on said vessel for reeling in a line connectible to said anchor and extending generally longitudinally of said deck, and anti-friction support means on said bridge structure intermediate said tracks for supporting said line extending generally longitudinally of said deck from said winch over said support means to said anchor, said tracks being spaced from each other by a distance greater than the width of the anchor to be handled, so that said anchor may freely pass between said tracks, and the space between said tracks and above said deck being free of obstructions which would interfere with the movement of said anchor, whereby said anchor may be freely moved longitudinally of said deck between said tracks by said bridge structure and deposited at a desired location on said deck intermediate said tracks. said tracks being essentially straight throughout their effective length and including a portion which is cantilevered beyond the edge of said deck during the operation of said bridge structure whereby said bridge structure may be selectively positioned outboard of said vessel.
 2. The apparatus of claim 1 wherein power means are provided on said bridge structure for moving said bridge structure longitudinally of said deck, said power means comprising an electric motor powered driver on said bridge structure in driving engagement with one of said tracks whereby said bridge structure may be driven along said tracks in either direction longitudinally of said deck.
 3. The apparatus of claim 1 wherein said anti-friction support means of said bridge structure comprise a pair of idler sheaves adapted to receive said line and support said line above said bridge structure, whereby frictional engagement between said line and said bridge structure is prevented.
 4. An anchor handling apparatus comprising: a buoyant vessel having a deck for receiving an anchor, a pair of elevated tracks disposed adjacent opposed sides of said deck and extending longitudinally of said deck, a transverse bridge structure extending between said tracks and movable longitudinally of said deck along said tracks, a powered winch on said vessel for reeling in a line connectible to said anchor and extending generally longitudinally of said deck, anti-friction support means on said bridge structure intermediate said tracks for supporting said line extending generally longitudinally of said deck from said winch over said support means to said anchor, and a bridge crane mounted on said bridge structure and adapted to move transversely of said bridge structure.
 5. In an anchor handling vessel having a winch adapted to reel in a line extending longitudinally of said vessel and connected to an anchor and a deck adapted to receive the anchor, the improvement comprising: a pair of straight elevated tracks spaced from each other and disposed longitudinally of said deck, a bridge structure disposed transversely of said deck, and mounted on said tracks foR movement longitudinally of said deck, anti-friction support means on said bridge structure for supporting said line extending longitudinally of said deck between said anchor and said winch, and a bridge crane assembly mounted on said bridge structure and movable transversely of said deck along said bridge structure.
 6. The apparatus of claim 5 wherein said anti-friction support means comprises at least one idler sheave disposed on top of said bridge structure to support said line above said bridge structure and wherein said idler sheave and said bridge crane are so configured that said bridge crane may pass freely under a line in said sheave.
 7. An apparatus comprising: a vessel having an elongated rear deck for receiving objects lifted over the stern of said vessel, a winch on said deck with a winch line extending generally longitudinally of said deck and adapted to be connected to objects to be lifted onto the deck, a pair of elevated tracks disposed longitudinally of said deck along opposite transverse edges thereof, a bridge structure extending transversely between and mounted on said tracks for movement longitudinally of said deck, an idler sheave on the upper side of said bridge structure adapted to receive and support said winch line above said bridge structure, and a bridge crane mounted on said bridge structure for movement transversely thereof and adapted to pass freely under said winch line in said sheave. 